Tories



H. F. WEISS.- I A METHOD AND APPARATUS FOR'THANSFORMLNG WOOD.

APPLICATXON FILED NGV. 16, 192i.

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H. F. wmss. METHITD AND APPARATUS FOR TRANSFORMIN G WOOD.

APPLICATION HLE D NOV. 16, [921. I

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UNITED STATES PATENT OFFICE.

HOWARD F. WEISS, or MADISON, wIscoNsIN, ASSIGNOR T0 cl r. BURGESSLABORA- ronms, or MADISON, wIscoNsIN, A CORPORATION or wIscoNsIN.

METHOD AND APPARATUS FOR TBANSFORMNG WOOD.

Original No.-1,366, 225, dated January 18, 1921, Serial No. 195,012,filed October 6. 1917. Application for reissue filed November 16,

To all whom 6i) may concern:

Be it known thatI, HOWARD F. l VEIss, a citizen of the United States,residing at Madison, in the county of Dane, State of Visconsin, haveinvented certain new and useful Improvements in Methods and Apparatusfor Transforming \Vood; and I do hereby declare the following to be afull, clear, and exact description of the invention, such aswill enableothers skilled in the art to which it appe'rtains to make and use thesame,

This invention relates to the transforming or coloring or fuming ofwood, and to the production of a novel product in the form of thetransformed or colored or fumed wood;

and the invention includes the new product as well as the method andapparatus for its production.

The invention is based upon the discovery that wood can be uniformly orhomogeneously transformed or colored and thereby converted into adarkened product of rich color by subjecting th wood to the propertemperature for the required period of time and by maintaining uniformconditions during the treatment.

According to the present invention, the wood is heated to a temperatureof about 380 F. to 420 F. for producing the best results, and ismaintained at such temperature and uniformly subjected to th heattreatment for the proper length of time, for example, two or threehours, until the desired conversion or transformation or coloring hasbeen effected and the heat treatment is uniformly applied tosi'ibstant-ially the entire surface of the wood during this period.

lVhile the drying of the wood to be transformed or colored may beeffected during or 'as an incident of the heat treatment, yet I havefound it to be more advantageous to use dried wood, preferably kilndried, before it is subjected to temperatures of over 300- F.; otherwisethe wood is liable to warp, split, check, etc.

In carrying out the process of the'present invention, I have found itessential to mamtain a temperature of over 300 F. in order to obtain thedesired transformation; and I have obtained best results withtemperatures ranging between about 380 F. and 420 F., inasmuch as it ismore difiicult to produce 1921. Serial No. 515,5602;

the dark, warm tones of color desirable at temperatures below 380 F.unless the wood is held at such temperatures for an mpracticable lengthof time. On the other hand,

temperatures above i20 I". tend to char and destroy the wood, and togive an unsatisfactory product. i I

In the carrying out of the process of the invention, itis essential notonly toi'nain-i tain the proper temperatures during the transformation,but likewise to apply the,

heat treatment uniformly,i; e. so that substantially every part of thesurface thereof is subjected to the same temper atureii-i rder that thewood may be evenly colorexor transformed; inasmuch as heating to thetemperatures above referred to, without uniform application of heat,will prevent the unlformity of treatment which is desired.

-wood in the interior of the retort or receptacle was relatively littlecolored or affected;

and even where coloring took place; the results obtained were notuniform.

Accordingly, in the carrying out of the process of the presentinvention. the heattreatment is uniformly applied so that unevenlvtransformed and unsatisfactory produc-ts will be avoided.

I have found it particularly advantageous to carry out thetransformation with heated air by bringing the heated air into contactwith the wood to betransformed and by regulating the temperature of theairso that it will uniformly or homogeneously trans form the wood withwhich itis brought in contact.

Inasmuch as the wood to be transformed requires a support during thistreatment, and inasmuch as a stationary support which would'cover anyconsiderable part of the woodwould cause unevenness in the coloring ortransforming, I have found it of 1mportance to so support the wood thatit W111 the wood and around the stickers.

beuniformly treated even at the places of support. Thus the ordinarywood stickers wvhich' are commonly, used-in stacking the lumber willleave a lighter streak upon the lumber with which they are in contact.In order to avoid such streakmg ofthe wood,

'I provide "for the movement of the stickers during the treatment sothat no one place will be unevenly colored; or I provide movablesupports which will support the wood at different places progressivelyduring the treatment; or I provide stickers which may remain stationarybut which are of an openwork construction (such as I-beams) so that theheated air may circulate freely around here the stickers are in the formof I-beams with edges which are not more than one-eighth of an inchthick, the aircan pass readily through them between the edges. Thesestickers can, of course, be moved to further minimize any danger ofuneven coloration. ith stickers which have a wider bearing surface onthe wood, their movement into contact with other surfaces of the woodcan be effected in any suitable manner. 'hen the wood is supported inthe form of a single layer upon movable supports or conveyers. such aschains, the lumber may be earned along slowly by the chain or chalns, orupon small skids secured thereto, set at a slight bevel or slant, sotnat the lumber will be supported at different places along its surface.ature for the required period of time, and

- during the third of which it is cooled by *50 the circulation of airin contact therewith; the

. heated air resulting from the cooling, of the lumber being used topreheat the fresh lumber in the first stage of the process.

It will be evident that various types and. constructions of apparatusare available for thecerrying out of the process of the presentinvention; and that, when the process is to beicarried out in the threestages above re ferred to,various types and constructions of apparatuswill likewise be available for this three-step process. I have found theapparatus illustrated, more or less conventionally and diagrammatically,in the accompanying drawings, tobe well'adapted to the practice of tlIBihVGDtIOII; and the nvention will be further described in connectiontherewith, but it will be understood that the more specific descriptionand illustration are intendedas illustrative ofthe invention and not aslimiting its intent and scope. In the accompanying drawings,

' Figure 1 is a plan view of an apparatus embodying the invention andadapted for the practice of the process of the invention and theproduction of the novel'product of the invention; i

Fig. 2 is a vertical sectional view of the central .or transformingchamber of Fig, 1. taken on line 2-2 of Fig. 1;

Fig. 3 is a longitudinal section taken on line 3-4-3 of Fig. 1;

Fig. 4i is a front elevation, with parts broken away,further"illustrating the construction of the apparatus; and

-Fig. 5 is a vertical. sectional view, enlarged, taken on line 55 ofFig. 2, and illustrates the manner of stackingthe"lumher on the I-beamstickers.

T heapparatus, illustrated is made up of three chambers,1, 2 and 3 inwhich the heating and transformation is to be carried out, thesechambers being provided with suitable walls for retaining the heattherein. The chamber 1 is the preheating chamber in which the preheatingof the lumber takes place, and this chamber is provided with suitabletracks l by means of which the lumber is introduced. As illustrated inFig. --i', the lumber is placed upon a truck 7 which is in turn carriedby a transfer table 6 which is run into the preheating chamber 1 throughthe side of the preheating chamber on the tracks a. A door 5 is providedfor the admission and removal of the transfer table.

Between the preheating chamber l and the transforming chamber 2, andalso between the transforming chamber 2 and the cooling chamber 3 arearranged doors which open to permit the truck 7 to pass from one toanother of these chambers, the truck passing from the transfer table 6to the track 9 and thence to another transfer table 10 in the coolingchamber, the truckbeing removed from this transfer table through anotherdoor 11 in the front thereof on trackschamber to another and theintroduction and removal of the transfer table can be effected' by anysuitable means (not shown). In order to heat the apparatus, there isprovided a retort or boiler 13 Which"may be 12. The transfer of thetruck from one ranged and extend the entire height of the i apparatus,as wellv as along one sideof the transforming chamber, and. they areprowith small holes of proper size and,

iao

19. The main temperature control may be obtained by properly regulating.the

heater 13.

suitably spaced apart to enable the desired uniform distribution of theair therethrough to be obtained.

A similar series of pipes is provided at 17 on the other-side ofthetransforming chamber, and these pipes are connected with the suctlonside of the blower lit by means of a'connecting pipe 18 sothat theyfunction assuction pipes for withdrawing the air 'and the hot air isdistributed throughout the chamber and passes between the layers ofboards piled horizontally on the truck 7 after which the air is suckedout' through the pipes 17 and through return pipe 18 to the blower andheater. By the provision of proper regulating means for regulatingthetemperature of the air and of thermostats or thermometers forobserving the temperature within the transforming chamber, the des ireduniformity of temperature and of distribution of the hot air within thischamber and through and around the lumber can be obtained. A thermostat(not shown) maythus be provided connected with the damper 19 so that. ifthe temperature of the air in the transforming chamber rises above thatwhich is desired. cool air may be admitted into the circuit through thedamper The series of pipes 15. 16 and the series of pipes 17. arecarried by the doors between the various chambers and are re movedtherewith to permit the passage of the trucks from one chamber toanother. In the construction, illustrated. the feed and suction pipes 15and 17 are so connected by detachable couplings. 20 and 21 that they maybe readily connected and disconnected, when this IS desired.

In place of the series of perforated pipes 16 and 17. there canadvantageously be used two perforated plates of iron or other suitablematerial. tend to reduce frictionlosses. The plates will be fastened insuch a manner as to form two pockets, in one of which the air- Suclr aconstruction will taincd at the proper temperature and with thenecessary uniformity of distribution durin the transforming operation.

Yith the apparatus above described. the highly heated lumber from thetransfornr ing chamber will pass to the cooling chamber, where the heattherefrom is utilized to heat air. with accompanying cooling of thelumber itself. and the heated air is then circulated by means of ablower22 through a suitable connecting passage 2-3 to the preheatingchamber 1; where it is utilized to preheat the fresh lumber therein, thedis tribution of the hot air being effected in any suitable manner (notshown). By proper distribution of the cooling air in the cooling chamberand of the preheating air in the preheating chamber. the lumber can beuniformly preheated before entering the transforming chamber anduniformly cooled before passing from the cooling chamber. The lumber maythus be cooled to 100F. or less in the cooling chamber after which itcan be handled like ordinary lumber.

As above pointedout. the wood to be transformed. if the best results areto be obtained. should be wood which is dried, and preferably kiln driedwood, before it is subjected to the temperatures utilized in thepractice of the present invention.

here the lumber is passed through the transforming apparatus on a truck,and the air is circulated through the lumber in the manner. abovedescribed. I have found it advantageous to pile the lumber on the trucksand to separate the horizontal layers of the lumber or boards. indicatedby 30 in the drawing by means of stickers made of one inch I-beams.indicated by 31 in the drawing. these stickers being placed so that theweb of the beam is horizontal. These I-beams may be spaced apart aboutthree feet. although the number used and their arrangement will varywith the kind of wood to be treated. Certain 110 woods tend to curl andtwist more than others, and. such woods will generally require morestickers than woodwhich tends to remain flat. Such one inch I-beams havetheir contacting edges of a thickness of only 115 about one-eighth of aninch and these edges are spaced apart so that the hotair can circulatebetween the webs of the I-beams and the lumber. Any objectionableunevenness in coloration or transformation will 120 thus be overcomewholly or in part.

In the carrying out of the process of the invention in the apparatusabove described, with the wood stacked on the truck or car in the mannerreferred to, the wood will be pre- 125 heated in the preheating chamberby the c1rculation of the air from the cooling chamber in contacttherewith, and the lumber thus prehatedwill then be. passed to thetransforming chamber where it will be heated to 13 formed or coloredby-the a temperature of 380 F. to d 'F. for a suitable period of,time,usuallyabout two tothree hours, the heatwbeing uniformly applied and thelumber being uniformly trans proper circulation 1 and uniformity ofdistribution of the heated to its place of storage or of furthertreatment' or use. The carrying out of the process in this way willinvolve a material conservation of heat because of the recovery of heatfrom the transformed lumber and the utilization thereof forpreheatingthe fresh lumber. The transformation can be carried o,ut, although withless economy of heat by omitting the preheating stage of the treatmentandby allowing the transformed lumher to cool without recovery of heattherefrom, by introducing the lumber directly. into the transformingchamber, but this will require a correspondingly increased period oftime for the transformation because the lumber must first be brought to'a temperature of about 380? F. and then heldthere for the necessaryperiod of time, or example, two

7 or three hours.

' between the chambers will be opened When the apparatus. abovedescribed is in operation, it will be evident that the preheating andcooling operations may be carthat the transforried out at the, same timemation is taking place, so that when one truck is ready to go to thecooling chamber. another truck will be ready to go from the preheatingchamber .to the transforming chamber. This transfer of: trucks will beeffective by suitable mechanism and the doors for the transfer.

The results obtained by the heat treatment and transformationprocess ofthe present invention will give somewhat different results withdifferent kinds of wood, but the general effect will be to darken thewood and giveto it arich brown coloration varying somewhat in depth ofcolor with the.

wood treated, with the particular temperature used in the treatment, andwith the duration of the treatment. It will thus be evident that thetransformation may be carried to aniextent which will give somewhatdifferentshades by the proper selectionof the lumber and by varyingsomewhat the 7 period and the particular temperature of thetransformation.

[according to the present invention will. ac.-

, cordingly be characterized by the changes whichtakeplace 'during thetransformation and which result in" the conversion of the lighterwoodinto a superior darkened prodby the cirof the present inventionThetransformed or cool-ed wood produced uct. Thus, inthe case of oak,the trans-v formation process of the present invention changes 'the oakfrom itsnatural light color 'to a rich brown, somewhat similar to thesocalled fumed oak or light mission oak. The transformation, moreover,takes place with a change in the wood itself such that the entire woodstructure is'given the'rich brown color. The transformed orcoloredw'ood'is thus colored with such uniformity and to such apleasingshade that it becomes immediately, without further treatment, a com-'mercial productwhich is available for use wherever a superior darkenedor colored wood is desired. I

The product of the present invention is moreover .one which issubstantially free from streaks or inequalities in the coloring ortransformation, so that it is available for use where a product ofstandard and uniform qualities is required. 'The product is thusdistinguished from lumber which is streaked because of improper piling,or which is unevenly colored or transformed their appearance.

- The product of the present invention is, moreover, a product "in whichthe wood has been changed or decomposed. although not in anobjectionable. sense, with the resultf that the wood retains itscharacteristic liar-dness but'becomes less elastic in character. Thisreduction in-elasticity is unobjectionable, and may even be advantageoimany purposes,.for whichthe lumber i where elasticity is not ofparticular.importance, e. g.. for flooring, trimming, etc. v

The product of the present invention is furthermore one characterized bymaterially reduced hygroscopic properties so that I its shrinkage andswelling qualities are very materially reduced. This reduction in thehygroscopic, properties of the wood and re duction in the tendency toshrink and swell is of particular importance for many pur poses. sincethe product may require little or no additional protection (e, bypainting. etc.,) to prevent objectionable swelling and shrinking thereofThis advantage. moreover, is independent of or in addition to theadvantage of coloration of the 'wood; although these advantages areaccumulative vwhen the desired col'oration is also obtained. Thus, quiteaside from any advantage of col oring which may be obtained. the productv has been found to shrink and swell about 50% less than the naturalwoodwhen exposedto the humidity changes of the air. The product can thus beused for high grade carperffi' freedom from checks,cracks and swellingis. greatl} desired. V

The process of the present invention. as 'will he readil understood, ismoreover of a relatively ple and inexpensive nature,

y work where .125

subjecting the wood to a temperature of about 380 F. to 420 F. in agaseous'atmosphere and maintaining all parts of the wood at suchtemperature for a sufficient period of time to transform the wood into ahomogeneously colored or darkened product with reduction of itshygroscopic properties, substantially as described. 1

2. The method of homogeneously transforming and coloring wood whichcomprises subjecting the wood to a temperature of about 380 F. to 420 F.by circulating a current of heated air in contact with substantially.the entire surface of the wood, and continuing the treatment of the woodby this means for a suificient period of time to trans form the woodinto a homogeneously colored or darkened product.

3. The method of homogeneously transforming and coloring wood'whichcomprises preheaping the heated wood to a temperature of about 380 F. to420 F. by circulating heated air in contact with substantially theentire surface of the wood, continuing the treatment at the specifiedtemperature until the wood is transformed into a homogeneously darkenedor colored product, cooling the transformed wood by circulation of airin contactthere,

with. and circulating the heated air resultthe cooling chamber to coolthe wood therein ing from the cooling of the wood into contact with thelumber before transformation in order to preheat the same.

4. The method of homogeneously transforming and coloring wood whichcomprises drying the wood at a temperature of about 150 F., subjectingthe dried wood to a temperature of about 380 F. to 420 ina gaseousatmosphere, and maintaining all parts of the wood at such temperatureunt1l the wood has been transformed into a homogeneously darkened orcolored product.

5. The method of homogeneously transforming and coloring wood whichcomprises subjecting the wood to a dry heat of about 380 F. to 420 F.for a period of about two to three hours, maintaining all parts of thewood at such temperature during such period, whereby the wood istransformed into a homogeneously darkened or colored product,substantially as descrlbed.

6. The method of homogeneously trans.- forming and coloring wood whichcomprises preheating the wood to a temperature of about 150 F. by.circulation. of heated air into contact therewith, subjecting thepreheated wood to a temperatureflfnbout 380 F. to 420 F. by circulationof heated air into wood, subjecting the precontact therewith and bymaintaining substantially all parts of the wood at this temperatureuntil the wood has been transformed into a uniformly darkened or coloredproduct, withdrawing theair utilized for the heating andagaincirculating the same after further heating into contact with thewood duringthe treatment, cooling the treated wood by circulation ofcooling air into contact therewith and thereby preheating the air andcirculating the preheated air into contact with the wood to preheat thesame andsimultaneously to increase the moisture content of the airbefore subjecting it to a temperature of about 380 F. to 420 F.

7 The method'of homogeneously transforming wood.which comprisessubjecting the wood to a temperature of 380 F.,to 420 F..by circulatingin contact with the wood a heated gaseous current, withdrawing the gasand re-circulating the same after further heating until the wood hasbeen converted into a uniformly transformed product. 1 v

8. The method of homogeneously transforming and coloring wood, whichcomprises movably supporting the wood and subjecting the wood to atemperature 'of about 380 F. to 420 F. by circulation of heated air intocontact therewith, the wood-being moved with respect to-its supports sothat all surfaces of the wood are homogenously transformed.

9. An apparatus for transforming or coloring wood comprising apreheating cham--100 her, a transforming chamber, a' cooling chamber,means for circulating air through and for circulating the' resultingpreheated air through the preheating chamber to preheat the woodtherein, means for heating air to the required temperature and forcirculating the heated air through the transforming chamber, and meansfor supporting the wood in said transforming chamber to permitdistribution of the heated air into contact with substantially theentire surface of the wood.

10. An apparatus for transforming or coloring wood comprising atransforming chamber, means for so supporting thewood. therein as topermit circulation of heated air into contact with substantially theentire surface of the wood, means for heating air to a temperature ofabout 380 F. to 420 F. and for circulating the heated .air through saidtransforming chamber to heat the wood therein, means for admixing coolair with the heated air, and thermostatically controlled means forregulating said admixture.

11. An apparatus for transforming or coloring wood comprising apreheating chamber, a transforming chamber, a cooling chamber, means forcirculating air through the cooling chamber to cool the wood therep inand; for circulating the resulting preforming" viuunher at iiiii'ei'eiitplaces on its heated air through the preheating chamber surfaoe by theaid of movable supports so as to preheat; the) wood therein, means forhezita to permit uniform distribution of the heated 10 ing air to thorequired"temperature and for air into contact with the entire surface ofthe 5 circu lii t iiig the heated air through the trans wood beingtreated.

formiilg chamber,- and meu'ns for intermitfi In testimonywhereofl affixnlyignature.

tentlj support ng-the wood in said tra n s- HOWARD F. WEISS.

